Hello,
I accidentally purchased some of the Moonfire Faire items two times.
When I wanted to discard the duplicates I noticed that some of them can't be discarded.

It does not seem to affect all of them, but at least these items are affected:
Red Summer Top
Red Summer Halter
Red Summer Trunks
Red Summer Tanga

There are other Moonfire Faire items that have this too.

Thanks in advance.